Final answer:
The most important factor in determining the respiratory rate is arterial pCO2, sensed by chemoreceptors in the brain and blood vessels. When pCO2 levels increase, the respiratory rate increases to eliminate excess carbon dioxide.
Step-by-step explanation:
The most important factor in determining the respiratory rate is arterial pCO2, also known as the partial pressure of carbon dioxide in the arterial blood. Arterial pCO2 is sensed by chemoreceptors in the brain and blood vessels. When pCO2 levels increase, the chemoreceptors send signals to increase the respiratory rate, allowing for the elimination of excess carbon dioxide from the body.
In contrast, arterial pO2 (partial pressure of oxygen in arterial blood), alveolar pCO2 (partial pressure of carbon dioxide in the alveoli), and alveolar pO2 (partial pressure of oxygen in the alveoli) play secondary roles in regulating the respiratory rate.